tests(testopenai): add image-generation cassette and request scaffolding

Signed-off-by: Hrushikesh Patil <[email protected]>

Author: nutanix-Hrushikesh

tests/internal/testopenai/cassettes.go

@@ -135,6 +135,11 @@ const (
 	// CassetteEmbeddingsBadRequest tests request with multiple validation errors.
 	CassetteEmbeddingsBadRequest
 
+	// Cassettes for the OpenAI /v1/images/generations endpoint.
+
+	// CassetteImageGenerationBasic is a basic image generation request with model and prompt.
+	CassetteImageGenerationBasic
+
 	// Cassettes for Azure OpenAI Service.
 
 	// CassetteAzureChatBasic is the same as CassetteChatBasic, except using
@@ -189,6 +194,8 @@ var stringValues = map[Cassette]string{
 	CassetteEmbeddingsMaxTokens:    "embeddings-max-tokens",
 	CassetteEmbeddingsWhitespace:   "embeddings-whitespace",
 	CassetteEmbeddingsBadRequest:   "embeddings-bad-request",
+
+	CassetteImageGenerationBasic: "image-generation-basic",
 }
 
 // String returns the string representation of the cassette name.
@@ -213,6 +220,9 @@ func NewRequest(ctx context.Context, baseURL string, cassette Cassette) (*http.R
 	} else if r, ok := embeddingsRequests[cassette]; ok {
 		path := buildPath(cassette, "/embeddings", baseURL, r)
 		return newRequest(ctx, cassette, path, r)
+	} else if r, ok := imageRequests[cassette]; ok {
+		path := buildPath(cassette, "/images/generations", baseURL, r)
+		return newRequest(ctx, cassette, path, r)
 	}
 	return nil, fmt.Errorf("unknown cassette: %s", cassette)
 }

tests/internal/testopenai/cassettes/image-generation-basic.yaml

@@ -0,0 +1,60 @@
+---
+version: 2
+interactions:
+- id: 0
+  request:
+    proto: HTTP/1.1
+    proto_major: 1
+    proto_minor: 1
+    content_length: 105
+    host: api.openai.com
+    body: "{\n  \"model\": \"dall-e-2\",\n  \"prompt\": \"A simple black-and-white line drawing of a cat playing with yarn\"\n}"
+    headers:
+      Accept-Encoding:
+      - gzip
+      Content-Length:
+      - "105"
+      Content-Type:
+      - application/json
+      User-Agent:
+      - Go-http-client/1.1
+    url: https://api.openai.com/v1/images/generations
+    method: POST
+  response:
+    proto: HTTP/2.0
+    proto_major: 2
+    proto_minor: 0
+    content_length: 544
+    body: "{\n  \"created\": 1759925706,\n  \"data\": [\n    {\n      \"url\": \"https://oaidalleapiprodscus.blob.core.windows.net/private/org-lKxIBdltrjcFbzboW0t1hthB/user-EdKNxj0PjYS29CfjUcR77ybc/img-MigVWgAi6l5W3B31L6imFob3.png?st=2025-10-08T11%3A15%3A05Z&se=2025-10-08T13%3A15%3A05Z&sp=r&sv=2024-08-04&sr=b&rscd=inline&rsct=image/png&skoid=52f8f7b3-ca8d-4b21-9807-8b9df114d84c&sktid=a48cca56-e6da-484e-a814-9c849652bcb3&skt=2025-10-08T12%3A15%3A05Z&ske=2025-10-09T12%3A15%3A05Z&sks=b&skv=2024-08-04&sig=ex3I6RoFVH9hfNst8oloGtfBVA3o2aXvTI4cFtLVzlE%3D\"\n    }\n  ]\n}"
+    headers:
+      Alt-Svc:
+      - h3=":443"; ma=86400
+      Cf-Cache-Status:
+      - DYNAMIC
+      Cf-Ray:
+      - 98b58f7bde648af7-BOM
+      Content-Length:
+      - "544"
+      Content-Type:
+      - application/json
+      Date:
+      - Wed, 08 Oct 2025 12:15:06 GMT
+      Openai-Processing-Ms:
+      - "13265"
+      Openai-Project:
+      - proj_Ro6stNUOKIiLVqRr1zdjaFoh
+      Openai-Version:
+      - "2020-10-01"
+      Server:
+      - cloudflare
+      Strict-Transport-Security:
+      - max-age=31536000; includeSubDomains; preload
+      X-Content-Type-Options:
+      - nosniff
+      X-Envoy-Upstream-Service-Time:
+      - "13269"
+      X-Request-Id:
+      - req_c643aaa7f52258b2192d4c133d117e43
+    status: 200 OK
+    code: 200
+    duration: 13.632879292s

tests/internal/testopenai/image_requests.go

@@ -0,0 +1,27 @@
+// Copyright Envoy AI Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package testopenai
+
+// ImageCassettes returns a slice of all cassettes for image generation.
+func ImageCassettes() []Cassette {
+	return cassettes(imageRequests)
+}
+
+// imageGenerationRequest is a minimal request body for OpenAI image generation.
+// We avoid importing the OpenAI SDK in tests to keep dependencies light.
+type imageGenerationRequest struct {
+	Model  string `json:"model"`
+	Prompt string `json:"prompt"`
+	// Optional fields like size/quality/response_format can be added later if needed.
+}
+
+// imageRequests contains the actual request body for each image generation cassette.
+var imageRequests = map[Cassette]*imageGenerationRequest{
+	CassetteImageGenerationBasic: {
+		Model:  "dall-e-2",
+		Prompt: "A simple black-and-white line drawing of a cat playing with yarn",
+	},
+}

tests/internal/testopenai/image_requests_test.go

@@ -0,0 +1,27 @@
+// Copyright Envoy AI Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package testopenai
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestImageCassettes(t *testing.T) {
+	testCassettes(t, ImageCassettes(), imageRequests)
+}
+
+func TestNewRequestImages(t *testing.T) {
+	tests, err := buildTestCases(t, imageRequests)
+	require.NoError(t, err)
+	for i := range tests {
+		// Currently only basic happy-path image generation cassette
+		tests[i].expectedStatus = http.StatusOK
+	}
+	testNewRequest(t, tests)
+}